RE: 1526 printer - repair(able) or not?

From: Martin Hoffmann-Vetter <>
Date: Mon, 9 Feb 2015 21:40:42 +0100
Message-ID: <00fa01d044a8$acee0960$>
Hello Ville,

> Sorry for not responding to some of you whom I asked about the print
> heads. I put the printhead away and collected some courage before
> trying it again.

That's a good idea.

> I have now managed to re-assemble the printhead. The problem was
> mainly to figure out the order in which the pins go in and how their
> lifters should go in. And which way the head should be assembled in
> the first place! It's a pretty clever arrangement, and while this was
> complex to assemble, I don't want to even imagine how the newer
> 24-pin/more heads are built!

Yes, this sounds very good. Congratulation!

> I still have the one missing pin on the print, but for the moment
> I'll leave it like this. The machine works and I wasn't really
> planning to publish anthing printed with it :)

It's possible that a needle driver has an error. So a defunc transistor or
anything else. For the first try i would swap two pins to the needles. If
the error moves too, the printhead is okay, if not the driver is okay. The
other failure (if the error moves) can be a riot port bit. So you can swap
the two riots or only two pins to the needle drivers.

There is a schematic at
for the 4022. I think the needle drivers are the same. You will find the
74LS06 (i think at your board this must be the 74LS05) and a transistor. So
you can check the 74LS05 or the transistor!

> I added a couple of pics, two inside shots of the printhead, too.
> Here:
> The blue resistor was used to hold the pins together during assembly
> of the lifters.



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Received on 2015-02-09 21:00:05

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